The present invention relates to the deposition of devices, such as medical devices, in inaccessible locations, such as blood vessels, particularly to a micro device for repositioning or retrieval of deposited devices, and more particularly to a micro device using shape memory polymer patches for re-attaching to such a deposited device to enable repositioning or retrieval thereof, and to a method for fabricating the micro device. There are medical applications which require the release of a device (e.g., stent, embolic coil) into a blood vessel usually through a catheter or attached to an end of a guidewire. Accurate placement of the device in the blood vessel is usually critical both for a good outcome and to avoid severe complications (e.g., downstream emboli). Unfortunately, the pulsatile flow of blood through the vessels often moves the device as the positioning system is detached or released therefrom and removed from the body. The situation is compounded by the higher pressures from increased blood flow as the catheter, for example, is removed from the area and less of the vessel's volume is blocked. Because it is not possible to directly visualize the devices, x-ray shadowgrams (or angiograms ) are used, and because the volumes are small (millimeter and smaller blood vessels), finding and attaching to a released device is very difficult.
Similar type problems exist in the non-medical field, wherein, for example, components are assembled inside of complex machinery that cannot be opened, or material, such as filters, etc., must be deposited in inaccessible locations.
Thus, there exists a need for a means by which material or devices can be deposited in inaccessible locations, and if need be, repositioned or retrieved. This need is particularly applicable for medical applications involving the deposit of medical materials or devices at a critical location in a blood vessel, etc.
The present invention provides a solution to the above-referenced problems by providing a micro device which can be re-attached to a previously deposited medical device, for example, for repositioning or retrieval thereof. In addition, the micro device can be utilized to initially deposit the medical device. Thus, the present invention enables the use of a single micro device to deposit, reposition, or retrieve a medical device, for example, in a blood vessel. This is accomplished, for example, by the formation of hoops on the medical device and the formation of shape memory polymer (SMP) hooks on the micro device, whereby the SMP hooks and deposits a medical device by release of the hooks from the hoops on the medical device, or re-attach the hooks to the hoops of the medical device for repositioning or retrieval thereof. The SMP hooks are activated by heating to cause release of the hoops or by heating and cooling to cause re-attachment to the hoops.